1. Field
The disclosure relates to an internal combustion engine.
2. Description of Related Art
Japanese Patent Application Publication No. 2011-94557 (JP 2011-94557 A) describes a blow-by gas returning apparatus provided with an internal combustion engine. One end of this blow-by gas returning apparatus is connected to a crankcase, and the other end of the blow-by gas returning apparatus is connected to an intake passage downstream of a throttle valve. The blow-by gas returning apparatus includes a first blow-by gas passage. The blow-by gas is sucked into the first blow-by gas passage from inside the crankcase by negative pressure generated in the intake passage downstream of the throttle valve. This blow-by gas returning apparatus also includes a bypass passage, an ejector (jet pump), and a second blow-by gas passage. One end of the bypass passage is connected to the intake passage upstream of a supercharger. Also, the other end of the bypass passage is connected to the intake passage downstream of the supercharger. The ejector is provided in the bypass passage. The ejector includes a fluid inlet, a fluid outlet, and a fluid suction port. The ejector is configured such that, when fluid flows from the fluid inlet to the fluid outlet, the ejector draws in different fluid from the fluid suction port. One end of the second blow-by gas passage is connected to the crankcase. The other end of the second blow-by gas passage is connected to the fluid suction port of the ejector.
In JP 2011-94557 A, the fluid inlet of the ejector is connected to the other end side of the bypass passage which is the side downstream of the supercharger in the intake flow direction. Also, the fluid outlet of the ejector is connected to one end side of the bypass passage which is the side upstream of the supercharger in the intake flow direction.
When the pressure downstream of the supercharger becomes higher than the pressure upstream of the supercharger while the supercharger is operating, the pressure on the other end side of the bypass passage will be greater than the pressure on the one end side of the bypass passage. Therefore, air will flow from the other end side of the bypass passage toward the one end side of the bypass passage. That is, even if negative pressure is generated in the intake passage downstream of the throttle valve, if the supercharger is operating, blow-by gas inside the crankcase is able to be drawn into the bypass passage by the ejector. Thus, the crankcase is able to be ventilated. One example of a state in which negative pressure is not generated in the intake passage downstream of the throttle valve is when the throttle valve is fully open.